Speed responsive transmission

ABSTRACT

This invention relates to improvements in a control mechanism for fluid-operated automatic speed change mechanisms of an automotive vehicle which comprises a fluid coupling having a pump wheel and a turbine wheel, with an adjusting valve adapted for increasing the hydraulic line pressure in response to a signal from a first sensor sensing an increase in the rotational speed of the pump wheel and adapted for decreasing the hydraulic line pressure in response to a signal from a second sensor adapted for sensing an increase in the rotational speed of the turbine wheel.

United States Patent May 16, 1972 Hirozawa 54] SPEED RESPONSIVETRANSMISSION [72] I t Koichiro Hirozawa, Kariya,.lapan [73] Assignee;Aisin Seiki Kabushiki Kaisha, Kariya Aichi Pref., Japan [22] Filed: May26, 1970 [21] App]. No.: 40,651

[30] Foreign Application Priority Data May 30, 1969 Japan ..44/42840[52] US. Cl.. ..74/731 [51] Int. Cl ..F16h 47/08 [58] Field ofSearch..74/73 1 645; 192/3.33

[56] References Cited UNITED STATES PATENTS 2,302,714 11/1942 Pollard..74/731 X 2,404,657 7/1946 Roberts et al.. ...74/731 X 2,699,074 l/1955Livezey et a1 ..74/645 2,913,931 11/1959 Hilpert ..74/731 2,970,498 2/ l961 3,556,271 1/1971 Hilpert ..l92/3.33

Primary Examiner-Carlton R. Croyle Assistant Examiner-Thomas C. PerryAtromey-Sughrue, Rothwell, Mion, Zinn & Macpeak [57] ABSTRACT Thisinvention relates to improvements in a control mechanism forfluid-operated automatic speed change mechanisms of an automotivevehicle which comprises a fluid coupling having a pump wheel and aturbine wheel, with an adjusting valve adapted for increasing thehydraulic line pressure in response to a signal from a first sensorsensing an increase in the rotational speed of the pump wheel andadapted for decreasing the hydraulic line pressure in response to asignal from a second sensor adapted for sensing an increase in therotational speed of the turbine wheel.

5 Claims, 2 Drawing Figures 191 I90 E I98 I 1 194 f I I95 197 I92 I03I19 29 II5 IIs I14 I02 180181 I77 I82 we '83 I 7 I I I 52 7 a 4 7'2 7 Im I65 w. 166 I5 I72 I I76 I55 I 2162 I59 I 3 SPEED RESPONSIVETRANSMISSION This invention relates to improvements in and relating to acontrol mechanism for the fluid-operated automatic speed changemechanism of an automotive vehicle.

This kind of automatic speed change mechanism comprises generally atleast a fluid delivery pump; and a plurality of valve means adapted forcontrolling the pressure fluid flows to be supplied to severalfluid-operated clutch units and brake units arranged for adjustingseveral gearings in the speed change mechanism, these valve means beingso designed and arranged that each of them controls the related oil flowin an accurate and precise way over a wide range of the workingconditions, so as to provide a possible highest performance at everyfunctional stage of the speed changer. Therefore, it must be sensitivelyoperative to the every vehicle running and loaded conditions. As anexample, the function controlling line pressure must be preciselycontrolled so as to meet with every working condition of the speedchange mechanism as the occasion may desire within a specificallyadopted operation range thereof. Under a heavy load condition as metduring the starting period of the automotive vehicle, the line pressureshould be controlled to a certain high value for providing hydraulicallyoperated clutch units or brake units with ample engaging efforts, so asto transmit a higher output power from the drive engine to the drivenvehicle wheels. On the contrary, when the vehicle runs at a high speedor under a lightly loaded condition, the transmitting torque isnaturally relatively small, thus the line pressure being set to a lowerlevel, and it is highly desirous to perform the engagement anddisengagement of the clutch or brake means provided at several placeswithin the speed change mechanism with the least possible shock. It willthus be seen from the foregoing that the function control of theautomatic speed change mechanism must be so that the hydraulic linepressure is adjusted depending upon the vehicle running condition. Inthe prior art automatic speed change mechanism, therefore, thearrangement is such that for satisfying the aforementioned contradictoryrequirements, the line pressure is controlled as a function of theengine throttling degree and the vehicle travelling speed in a certainartificial way. In an alternative way, an accumulator, orifice controlvalve or the like means is used for the generating of a time lag in theline pressure oil supply to or oil discharge from the clutch or brakemeans. According to our experiments, these prior proposals are far fromthe ideal. Especially, substantial obviation of clutching or brakingshocks is not satisfied which constitutes naturally a drawback inherentof most concern in the practice of the prior art.

The main object of the invention is to provide an efficient controlmechanism for an automatic automotive speed change mechanism capable ofsubstantially obviating the hitherto unavoidable clutch shocks appearingin the course of the speed change operation.

In the control mechanism of the above kind and embodying the novelprinciples of the invention, means are provided for detecting thevariation in the speed ratio of the speed change mechanism that is, theratio between the input revolutions and the output revolutions at thetorque converter contained in the speed changer, and a further meansadapted for controlling said line pressure in response to the thussensed variation under every load and running condition of the vehicle.

A further object is to provide an improved control mechanism of theabove kind by which conventionally encountering shocks caused by speedchange operations can be substantially reduced.

These and further objects, features and advantages of the invention willbecome more apparent when reading the following detailed description ofthe invention by reference to the accompanying drawings, in which:

F IG. 1 is a schematic and explanatory half view of essentialpower-transmitting constituents of an automatic fluidoperated speedchange mechanism which is adapted for cooperation with the controlmechanism according to this invention.

FIG. 2 is a substantially sectional general arrangement view of thecontrol mechanism according to this invention shown in its preferredembodiment.

Referring now to FIG. 1, illustrative of essential powertransmissionparts of an automotive automatic speed change mechanism of theconventional forward two speed and backward one speed type, the numeral10 denotes a drive or input shaft which consists of the crank-shaft of adrive or internal combustion engine, not shown, fitted on a automotivevehicle, not shown, while the numeral 29 represents a driven or outputshaft adapted for driving automotive vehicle wheels, not shown, and 17denotes an intermediate shaft arranged between the input and the outputshaft. As may be well supposed, these input, intermediate and outputshafts are arranged coaxially one after another and mounted rotatablywithin the casing of the speed changer. Since this speed changer per seis of the conventional design, the casing is shown only partially and ina highly simplified way at 16. In this housing 16, a torque converterunit 11, a planetary gearing unit 21, a clutch unit 18, a front brakeunit 19 and a rear brake unit 20 are also provided as seen, all theseunits being of the conventional design.

The torque converter unit 11 comprises a pump wheel 12, a turbine wheel13 and a stator wheel 14 as in the conventional way. Pump wheel 12 isfixedly attached through a carrier 300 onto the input shaft 10, saidcarrier being shown only in a highly simplified way by a line. Turbinewheel 13 is fixedly mounted on the intermediate shaft 17 through afurther carrier 301 and stator wheel 14 is mounted through one way brakeunit 15 on a first sleeve shaft 30 which is rigidly mounted through aconnecting member 302, shown only schematically by a straight line, withthe stationary housing 16.

Planetary gearing unit 21 comprisesa first sun gear 28, a second sungear 22, a ring gear 24, a first set of planetary gears 23, of largergear thickness, of which only one is representatively shown, and asecond set of planetary gears 27 of shorter gear thickness, of whichonly one is shown again, all these planetary gears being rotatablymounted on a carrier 26 shown again in a highly simplified way.

First sun gear 28 is rigid with the intermediate shaft 17 and second sungear 22 is made rigid with a second sleeve shaft 31 which is made rigidwith the drum at 18a of clutch unit 18. Gear carrier 26 is made rigidwith the output shaft 29. Ring gear 24 is made as part of the drum 25which is rotatably mounted on the output shaft and rolatable relativethereto.

Planetary gears 23 are kept in mesh with ring gear 24, second sun gear22 and planetary gears 27. Clutch unit 18 can operate to couple secondsun gear 22 with first sun gear 28 into a rigid unit. Both sun gears 22and 28 are then driven by the intermediate shaft 17. More specifically,first sun gear 28 is driven bythe shaft 17 when the clutch 18 is kept inits disengaged position, while both gears 22 and 28 are driven simultaneously by the same shaft when clutch 18 is engaged.

Brakes 19 and 20 are arranged so as to apply braking effort onto therespective drums 18a and 25 for bringing second sun gear 22 and ringgear 24 into respective stationary position. Clutch unit 18 and brakes19 and 20 are respectively of the known conventional design andarrangement. The speed changer is so designed and arranged so as toprovide a high speed forward step, a low speed forward step and a singlerearward speed step, as will be more fully described hereinafter.

With the clutch l8 and brakes 19 and 20 kept in their disengagedposition, the transmission is kept in its neutral position, thereby noneof driving torque being transmitted from input shaft 10 to output shaft29.

When front brake unit 19 is brought into engagement so as to brake therelated drum 18a for bringing second sun gear 22 into its stationarycondition, while clutch unit 18 and rear brake unit 20 are kept in theirdisengaged position, the automotive vehicle is ready for starting. Inthis case, second sun gear 22 will act as a reaction member for theplanetary gear unit 21 and the engine torque will be transmitted frominput shaft 10 through torque converter 11, intermediate shaft 17,

first sun gear 28, planetary gears 25; 27 and gear carrier 26 to outputshaft 29. As was briefly hinted hereinbefore, the output shaft ismechanically connected through a certain mechanical means, notshown, toa drive wheel, not shown, which is arranged to drive the vehicle wheels.

When it is desired to transmit a high speed driving force, clutch unit18 is engaged and brake units 19 and 20 are brought into theirdisengaged position. With the unit 18 engaged, both sun gears 22 and 28are united together and planetary gear unit 21 is brought into its fixedposition so that a direct coupling between the intermediate shaft 17 andthe output shaft 29 is realized.

The rearward drive for the vehicle is realized by actuating the rearbrake unit 20 and releasing the front brake unit 19. In this case, theengine drive torque is transmitted from input shaft 10, torque converter1 1, intermediate shaft 17, gears 27; 23 and gear carrier 26 to outputshaft 29.

Brake unit 20 acts to keep the ring gear 24 in its stationary positionso as to act as a reaction member. Thus, the forward drive torquesupplied to first sun gear 28 is reversed in its direction by theintermediary of planetary gear unit 21; and gear carrier 26 and outputshaft 29 are driven in the opposite direction to the rotational movementof the input shaft 10.

The control mechanism according to this invention and adapted forcontrol of the function of the automatic speed changer shown generallyin FIG. 1 is shown in its representative and preferred embodiment. n

In this control mechanism, there is provided a plurality of valves asfollows:

manually operatable valve 100; adjusting valve 101; throttle valve 102;shift valve 103; first governor valve 104; second governor valve 105;third governor valve 106; down shift valve 109;

There is provided a pump 107 which is driven from the drive engine fordelivering oil from a reservoir 108 to the aforementioned severalvalves. Pump 107 is connected through piping means 110 to adjustingvalve 101, manual valve 100 and first governor valve 105. Manual valve100 is connected through piping means 111 to valves 102 and 103; andthrough piping means 112 to third governor valve 106; and through pipingmeans 113 to the hydraulic working chamber of rear brake unit 20.Throttle valve 102 is connected through piping means 114 to shift valve103 which is connected in turn through piping means 115 to the hydraulicworking chamber of clutch unit 18; and through piping means 116 to thehydraulic working chamber of brake unit 19. The hydraulic pressures uponsubjected to control at valves 104 and 105 are applied throughrespective conducts 117 and 118 to the opposite ends of said valve 101.

Third adjusting valve 106 is connected through piping 119 to shift valve103.

Manual valve 100 comprises a valve housing 120 having a 1 longitudinalbore 121; and a spool valve member 133 mounted slidably in the latter.Valve bore 121 is kept in fluid communication with several ports 122;123; 124 and 125. Valve member 133 is formed with lands 126; 127 and 128as shown, thereby providing ring-shaped liquid spaces 129 and 130between each respective neighboring pair of said lands. Port 123 isconnected fluidically with the conduit 110; and port 122 is connectedwith the conduit 113. Port 124 is fluidically connected with conduit111; port 125 with conduit 112; and ports 131 and 132 formed at the bothends of valve bore 121 are arranged to serve as discharge openingsleading to oil reservoir 108, should the valve lands 126 and 128 notcover occasionally and selectively these ports. Valve 133 has fiveselectively shiftable positions or more specifically the parkingposition P"; the reverse drive position R; the neutral position N; theautomatic speed change position D" for low and high speeds; and theforward low speed position L." By the respective shift of the valvemember, various ports formed through the wall of valve housing maynaturally and differently connected with each other, as will be morefully described hereinafter.

Adjusting valve 101 has the function for control of the oil pressuredelivered from pump 107 and is provided with a longitudinal stepped bore135 formed in a valve housing 134; and comprises a spool valve member136 slidably mounted in said valve bore and an urging spring 147 forsaid valve member, the spring being mounted within said valve bore asshown.

Valve body or housing 134 is formed with several ports 137; 138; 140 and141 which fluidically communicate with the valve bore 135. Valve member136 is formed with several lands 142; 143 and 144. Land 142 has the samediameter as land 144; and land 143 has a larger diameter. Valve member136 is thus formed with ring-shaped liquid spaces 145 and 146. Port 137is connected hydraulically with conduit 110; port 138 with conduit 117;port 139 with conduit 118; and ports 140 and 141 are opened towards theliquid reservoir 108.

Throttle valve 102 and down-shift valve 109 is formed with a commonvalve bore 151 formed within its valve body or housing 150, and thecombined valve assembly comprises a throttle valve member 152 and adown-shift valve member 153 shiftably mounted within said valve bore, acompression spring 154 being inserted under pressure between these valvemembers.

Valve housing 156 is formed with ports 155; 156; 157; 158 and 159 whichare fluidically connected said valve bore 151.

Throttle valve member 152 is formed with valve lands 160 and 161 havinga common outside diameter and a ring space 162 formed therebetween.Down-shift valve 153 is formed with land 163 and arranged to beshiftable along its longitudinal axis when subjected to a manual forcetransmitted thereto from a conventional accelerator pedal 164 through aconnection means 165. By the provision of a positioning projection 166on the valve body 150, the down-shift valve is limited in the range ofits rightward movement in FIG. 2.

Port 155 is fluidically connected with piping means 111; port 156 and157 with piping means 114; while ports 158 and 159 are connected withoil reservoir 108, although the connection piping serving for thispurpose have been omitted for simplicity.

Shift valve unit 103 comprises a valve housing 170 formed with valvebore; and a shift valve member 172 slidably mounted in this bore, acompression spring 173 being pro vided for urging the valve member tomove leftwards in FIG. 2. Valve housing 170 is formed with ports 179;180; 181; 182; 183; 184 and 185 which are kept in communication with thevalve bore if the valve member does not block them.

Shift valve member 172 is formed with lands 174; 175 and 176 having acommon outside diameter; thereby two separate ring-shaped liquid spaces177 and 178 being formed.

Port 179 is fluidically connected with piping means 111; port 180 withpiping means 119; port 181 with piping means 1 15; port 182 with pipingmeans 116; and port 183 with piping means 114; ports 184 and 185 areopened to oil reservoir 108, although the connection means have beenomitted to oil reservoir 108.

Third governor valve unit 106 comprises a valve housing which isarranged to rotate in unison with output shaft 29 and formed with astepped bore 19] receiving slidably a spool valve member 192. A snapring 196 is positioned in the lower part of the valve housing 190 forlimiting the downward movement of the spool 192 towards 29 in FIG. 2.Valve member 192 is formed with a first land 193 and a second land 194,the latter having a smaller outside diameter than the former and aring-shaped liquid space being formed between these two valve lands.Valve housing 190 is formed with several ports 197; 198 and 199. Port197 is fluidically connected with piping means 119; port 198 with pipingmeans 112; while port 199 is opened to oil reservoir 108, although theconnection piping have omitted from the drawing for simplicity.

First governor valve unit 104 comprises a valve housing 200 having astepped bore 201 and being arranged for unitary rotation with the pumpwheel 12 of converter unit 11. The unit 104 is provided with a spoolvalve member 202 slidably receivedin the valve bore 201 and the wall ofsaid bore is provided with a snap ring 206 serving motion limiter forthe downward movement of valve spool 202 towards an axis 210.

Valve spool 202 is formed with a first land 203 and a smaller secondland 204, a ring groove 205 being formed therebetween. Valve housing 200is formed with several ports 207; 208 and 209. Port 207 is fluidicallyconnected with piping means 117; port 208 with conduit 110; and port 209is opened to oil reservoir 108.

Second governor unit 105 comprises a valve housing 211 which is formedwith a bore 212 and arranged to perform a unitary rotation with theintermediate shaft 17 rigid with said turbine wheel 13 of the converterunit 11. Valve spool 213 is formed with a first land 214 and a second orsmaller land 215, a ring groove 216 being formed therebetween. Valvehousing 211 is formed with ports 218; 219 and 220. Port 218 isfluidically connected with piping means 118 and port 219 with pipingmeans 110, while port 220 is opened to oil reservoir 108, although theconnecting piping has been omitted from the drawing only for simplicity.

The operation of the control mechanism so far shown and described is asfollows.

With the manual valve unit 100 kept in its neutral position N in FIG. 2,the driver starts the automotive engine for actuating the pump 107. Oilis therefore sucked from reservoir 108 by the pump 107 which deliverspressurized oil through piping means 110 to inlet port 137 of theadjusting valve unit 101; inlet port 123 of the manual valve unit 100;inlet port 208 of first governor valve unit 104; and inlet port 219 ofsecond adjusting valve 105.

Pressure oil supplied to inlet port 137 acts upon the differentialcross-sectional area between the valve lands 143 and 144 on valve spool136 and the latter is hydraulically urged against the action of returnspring 147 to move rightwards in FIG. 2. With the rightward movement ofvalve spool 136, port 140 is opened and oil is discharged therethroughto oil reservoir 108. Upon the opening of port 140 by the rightwardshift of valve land 143, the oil pressure in piping means 110 will bereduced, until the hydraulic force acting upon the differential areabetween valve lands 143 and 144 will become balance with the springforce at 147. In this way, the regulator valve unit 101 acts to regulatethe pressure level in the conduit menas 110. The thus adjusted pressurein the conduit 110, hereinafter called "line pressure" throughout thespecification, is conveyed to the inlet port 208 of first governor valveunit 104, the inlet port 219 of second governor valve unit 105 and theinlet port 123 of manual valve unit 100. Since the pump wheel 12 is keptin rotation, the valve housing 200 of unit 104 is also kept in rotationabout the shaft axis 210 so that valve member 202 is urged centrifugallyto shift upwards in FIG. 2, thereby the inlet port 208 being opened bythe removal of the hitherto closing valve land 204. Pressure oil willtherefore invade through the thus opened inlet port 208 into the bore ofthe valve unit 104 and act upon the differential area between the lands203 and 204. In this way, the valve member 202 will be urgedhydraulically against the aforementioned centrifugal force to movedownwards by which the land 203 will open the discharge port 209. Inthis way, governor valve unit 104 will adjust the output pressure fromconduit 207 in accordance with the occasional rotation of pump wheel 12or more specifically in function of the revolutional speed of the driveengine. This output hydraulic pressure from conduit 207 will be referredto as first governor pressure hereinafter.

Second governor valve unit 105 acts in the similar way to first governorvalve unit 104, a second governor pressure which is the output hydraulicpressure from the port 218 is delivered to the conduit 118, upon beingsubjected to an adjustment in function of the rotational speed of theintermediate shaft 17 which is equal to that of turbine wheel 13.

The line pressure fed from the conduit 110 to input port 123 of manualvalve unit is checked by valve land 127 on spool 133 from invading intothe corresponding valve bore.

The forward low speed drive mode is established by manipulating manualvalve 100 to either L"-position or position. With the valve spool 133positioned at L"-position, the line pressure prevailing in the conduitis fed to port 124 only on account of the closure of port 125 by valveland 128, thence through conduit 111 to both the inlet ports 179 and155. When the valve spool 133 is manually adjusted to either L- orD"-position at a low vehicle speed, valve member 172 of shift valve unit103 is urged by spring pressure at 173 to move leftwards, until port 179being brought into fluid communication'with the ring space 178 formedbetween valve lands 175 and 176, said space 178 being kept in fluidcommunication with port 182. Thus, the line pressure in conduit 111 willbe conveyed therefrom through port 179, ring space 178, port 182 andconduit 116 to the hydraulic working chamber 225 for actuation of brakeunit 19. Upon actuation of the brake unit 19, the low speed drive ratiois established as was referred to hereinbefore.

On the other hand, the line pressure will be conveyed through inlet portof throttle valve unit 102; ring space 162 on valve member 152; port157; conduit 114 and port 156 to the left-hand side of the land on valvespool 152. This hydraulic pressure counteracts the spring pressure at154 which spring has been further compressed from its initially insertedstate by the occasional shift of down-shift valve 153 upon manualactuation of acceleration pedal 164, the depression thereof beingtransmitted through the connection member or push rod to the valve spoolpart 153. When the thus applied hydraulic pressure exceeds the counteraction of the spring 154, valve member 152 is moved rightwards. Withrightward movement of valve member 152, the land 160 is brought intoregistration with port 155 so as to close it, while the land 161 willrecede from its closing position for the discharge port 158 which isthus opened.

With the discharge port 158 thus opened, the hydraulic pressure inconduit 114 is reduced, until it, now acting on the land 160, balancesthe spring pressure at 154. In this way, the throttle valve 102 controlsthe hydraulic pressure in conduit 114 in function of the depressedamount of the accelerator pedal.

The hydraulic pressure thus modulated by the throttle valve 102 will bereferred to as throttle pressure" hereinafter. This throttle pressure isconveyed from conduit 114 to the port 183 of .shift valve 103 so thatshaft valve members 172 is urged hydraulically to move leftwards.

With the manual valve 100 positioned at L, the valve member 172 is keptalways at its left position, because there is no counter-acting forceagainst the throttle pressure and the spring pressure at 173.

With the valve spool 133 of manual valve 100 positioned at D"-position,the line pressure is supplied through port 125 in valve housing 120;conduit 112; and port 198 in valve housing of third governor valve unit106, other operational features being substantially same as before withthe valve spool held at L-position.

Third governor valve 106 acts in the similar way with said first orsecond governor valve 104 or 105, and the third governor pressure uponsubjected to adjustment in function of the rotational speed of outputshaft 29 in terms of the vehicle speed is fed from output port 197 toconduit 112. The third governor pressure in the conduit 112 is appliednow to the left-hand side of valve land 174 on spool 172 of the shiftvalve unit 103 and counter balances the leftward urging force exerted byspring 173. So far as the third governor pressure is smaller than thecombination of the spring force 173 with the throttle pressure, theshift valve 172 is positioned at its lefthand end position in FIG. 2,thereby the low speed drive ratio being established.

On the other hand, when the third governor pressure force becomes largerthan the spring pressure 173 plus throttle pressure, shift valve 172will be shifted to the position in FIG. 2. By this valve shift, theinput port 179 adapted for reception of the line pressure is broughtinto fluid communication with the ring groove 177 formed between thelands 174 and 175 so that ports 179 and 181 are kept in fluidcommunication, and at the same time, port 182 hitherto kept incommunication with port 179 is brought into fluid connection with thedischarge port 185. This results in the actuation of clutch 18 and brake19 is released for establishing the high speed drive stage.

The down-shift from the forward high speed stage to the forward lowspeed stage is realized at a lower vehicle speed when the third governorpressure becomes smaller than the sum of spring pressure at 173 andthrottle pressure for urging the valve member 172 to the left-handposition.

A forced down-shift from the forward high speed stage to the forward lowspeed stage will be realized by depressing the accelerator pedal 164 toa certain limit destined for that function.

With the accelerator pedal 164 depressed so far, the spring 154 isfurther compressed in a corresponding way so that the left-hand end ofdown-shift valve 153 is brought into a direct contact with the throttlevalve 152 for urging the latter to move leftwards and the input port 155is uncovered by valve land 160. in this way, the throttle pressure inthe conduit 114 will become equal to the line pressure. Since the linepressure is higher than the governor pressure, the shift valve 172 ismoved towards left so that the low speed drive stage is realized. Thereverse drive stage is realized by manipulating the manual valve 100 toits R-pos ition. With this shifted position of the valve 100, the land127 on manual valve 133 will interrupt the fluid communication betweenthe ports 123 and 124, while inlet port 123 and port 122 are broughtinto fluid communication with each other through the intermediary ofring groove 129.

The line pressure fed to port 122 is conveyed further through conduit 113 to the hydraulic working chamber 226 of rear brake unit 20 which isthus actuated for the realization of the rear drive stage.

At this stage, conduits 111 and 112 is opened through port 132 to liquidreservoir 108 and thus the front brake l9 and the clutch 18 are kept intheir non-engagement or off-service position.

As will be clearly seen from the foregoing that according to the novelteachings of the present invention, means are provided for sensing therespective revolutional speeds of the input side member or pump wheel ofa converter or fluid coupling, and of the output side member or turbinewheel, and that a conventionally adopted adjusting valve means isconnected in opposition to a first and a second governor valve formodulating the hydraulic line pressure in response to the aforementionedrespective revolutional speeds thus sensed. In this way, the linepressure can be adjusted to respond to the engine output, on the onehand, and to the travelling resistance encountered with the runningvehicle, on the other hand. By relying upon such modulated linepressure, various hydraulically operated actuating elements or unitssuch as clutches and brakes contained in a conventional automatic speedchange mechanism can each provide an efiective engaging effort withoutinviting otherwise encountered considerable amounts of speed changeshocks.

In the foregoing, a kind of hydraulically governor was used as arepresentative way. Although not shown, however, an electric generatoror the like machine can be used in place of the hydraulic unit forsensing the rotational speed of the input or output constituent of thetorque converter.

The embodiments of the invention in which an exclusive property orpriviledge is claimed are defined as follows:

1. In a control mechanism for an automatic speed change mechanism havingan input shaft an an output shaft, a fluid coupling comprising a pumpwheel driven by a drive engine through said input shaft, a turbine wheeloperatively connected to an intermediate shaft, and a gearing meansoperatively connected to said intermediate shaft and driven thereby,said gearing means comprising friction-engageable means operativelyconnected to said gearing means for transmitting torque from said fluidcoupling to said output shaft, wherein the improvements comprise incombination: a fluid pressure source for supplying hydraulic fluidpressure to actuate said friction engageable means, passage meanscommunicating said fluid pressure source with said friction engageablemeans, pressure adjusting valve means communicating with said passagemeans for regulating the fluid pressure therein, a first sensor meansdrivingly connected to said pump wheel for sensing the rotational speedof said pump wheel and generating a first output signal, the output ofsaid first sensor means being operatively connected to said adjustingvalve means, and a second sensor means drivingly connected to saidturbine wheel for generating a second output signal in response to therotational speed of said turbine wheel, the output of said second sensormeans being operatively connected to said adjusting valve means, saidadjusting valve means acting to increase the hydraulic line pressure insaid passage means in response to said first output signal anddecreasing said line pressure in said passage means in response to saidsecond output signal.

2. A control mechanism as claimed in claim 1, wherein said first sensormeans comprises a first hydraulic governor means communicated with saidpassage means, said governor means acting to vary the output pressurethereof as a function of the revolutional speed of said torque converterpump wheel.

3. A control mechanism as claimed in claim 1, wherein said second sensormeans comprises a second hydraulic governor means communicated with saidpassage means, said governor means acting to vary the output pressurethereof as a function of the revolutional speed of said intermediateshaft, said intermediate shaft being coupled with said turbine wheel.

4. A control mechanism as claimed in claim I, wherein said first sensormeans comprises a hydraulic governor means for varying the outputpressure thereof as a function of the revolutional speed of said pump,and said second sensor comprises a hydraulic governor means for varyingthe output pressure thereof as a function of the revolutional speed ofsaid intermediate shaft, said intermediate shaft being coupled with saidturbine wheel, said first and second hydraulic governor means beingcommunicated with said passage means.

5. A control mechanism as claimed in claim 1, wherein said adjustingvalve means comprises a valve body formed with a stepped valve bore, avalve member formed with a first, second and third lands, said first andthird lands being slidably mounted within a small bore of said steppedbore and said second land being slidably mounted within a large bore ofsaid stepped bore for controlling a drain port, a first hydraulicchamber formed by said first land and connected to an outlet port ofsaid second sensor means, a second hydraulic chamber formed between saidfirst and second lands and connected to said passage means, a thirdchamber formed between said second and third lands in which a springmeans is inserted for urging said valve member against the hydraulicpressure of said first and second chambers, and a fourth hydraulicchamber formed by said third land for connecting to an outlet port ofsaid first sensor means.

1. In a control mechanism for an automatic speed change mechanism havingan input shaft an an output shaft, a fluid coupling comprising a pumpwheel driven by a drive engine through said input shaft, a turbine wheeloperatively connected to an intermediate shaft, and a gearing meansoperatively connected to said intermediate shaft and driven thereby,said gearing means comprising friction-engageable means operativelyconnected to said gearing means for transmitting torque from said fluidcoupling to said output shaft, wherein the improvements comprise incombination: a fluid pressure source for supplying hydraulic fluidpressure to actuate said friction engageable means, passage meanscommunicating said fluid pressure source with said friction engageablemeans, pressure adjusting valve means communicating with said passagemeans for regulating the fluid pressure therein, a first sensor meansdrivingly connected to said pump wheel for sensing the rotational speedof said pump wheel and generating a first output signal, the output ofsaid first sensor means being operatively connected to said adjustingvalve means, and a second sensor means drivingly connected to saidturbine wheel for generating a second output signal in response to therotational speed of said turbine wheel, the output of said second sensormeans being operatively connected to said adjusting valve means, saidadjusting valve means acting to increase the hydraulic line pressure insaid passage means in response to said first output signal anddecreasing said line pressure in said passage means in response to saidsecond output signal.
 2. A control mechanism as claimed in claim 1,wherein said first sensor means comprises a first hydraulic governormeans communicated with said passage means, said governor means actingto vary the output pressure thereof as a function of the revolutionalspeed of said torque converter pump wheel.
 3. A control mechanism asclaimed in claim 1, wherein said second sensor means comprises a secondhydraulic governor means communicated with said passage means, saidgovernor means acting to vary the output pressure thereof as a functionof the revolutional speed of said intermediate shaft, said intermediateshaft being coupled with said turbine wheel.
 4. A control mechanism asclaimed in claim 1, wherein said first sensor means comprises ahydraulic governor means for varying the output pressure thereof as afunction of the revolutional speed of said pump, and said second sensorcomprises a hydraulic governor means for varying the output pressurethereof as a function of the revolutional speed of said intermediateshaft, said intermediate shaft being coupled with said turbine wheel,said first and second hydraulic governor means being communicated withsaid passage means.
 5. A control mechanism as claimed in claim 1,wherein said adjusting valve means comprises a valve body formed with astepped valve bore, a valve member formed with a first, second and thirdlands, said first and third lands being slidably mounted within a smallbore of said stepped bore and said second land being slidably mountedwithin a large bore of said stepped bore for controlling a drain port, afirst hydraulic chamber formed by said first land and connected to anoutlet port of said second sensor means, a second hydraulic chamberformed between said first and second lands and connected to said passagemeans, a third chamber formed between said second and third lands inwhich a spring means is inserted for urging said valve member againstthe hydraulic pressure of said first and second chambers, and a fourthhydraulic chamber formed by said third land for connecting to an outletport of said first sensor means.